Added in API level 1

SocketImpl

public abstract class SocketImpl
extends Object implements SocketOptions

java.lang.Object
↳	java.net.SocketImpl

The abstract class SocketImpl is a common superclass of all classes that actually implement sockets. It is used to create both client and server sockets.

A "plain" socket implements these methods exactly as described, without attempting to go through a firewall or proxy.

Summary

Inherited constants

From interface java.net.SocketOptions

`int`	`IP_MULTICAST_IF` Set which outgoing interface on which to send multicast packets.
`int`	`IP_MULTICAST_IF2` Same as above.
`int`	`IP_MULTICAST_LOOP` This option enables or disables local loopback of multicast datagrams.
`int`	`IP_TOS` This option sets the type-of-service or traffic class field in the IP header for a TCP or UDP socket.
`int`	`SO_BINDADDR` Fetch the local address binding of a socket (this option cannot be "set" only "gotten", since sockets are bound at creation time, and so the locally bound address cannot be changed).
`int`	`SO_BROADCAST` Sets SO_BROADCAST for a socket.
`int`	`SO_KEEPALIVE` When the keepalive option is set for a TCP socket and no data has been exchanged across the socket in either direction for 2 hours (NOTE: the actual value is implementation dependent), TCP automatically sends a keepalive probe to the peer.
`int`	`SO_LINGER` Specify a linger-on-close timeout.
`int`	`SO_OOBINLINE` When the OOBINLINE option is set, any TCP urgent data received on the socket will be received through the socket input stream.
`int`	`SO_RCVBUF` Set a hint the size of the underlying buffers used by the platform for incoming network I/O.
`int`	`SO_REUSEADDR` Sets SO_REUSEADDR for a socket.
`int`	`SO_REUSEPORT` Sets SO_REUSEPORT for a socket.
`int`	`SO_SNDBUF` Set a hint the size of the underlying buffers used by the platform for outgoing network I/O.
`int`	`SO_TIMEOUT` Set a timeout on blocking Socket operations: ServerSocket.accept(); SocketInputStream.read(); DatagramSocket.receive(); The option must be set prior to entering a blocking operation to take effect.
`int`	`TCP_NODELAY` Disable Nagle's algorithm for this connection.

Fields
`protected InetAddress`	`address` The IP address of the remote end of this socket.
`protected FileDescriptor`	`fd` The file descriptor object for this socket.
`protected int`	`localport` The local port number to which this socket is connected.
`protected int`	`port` The port number on the remote host to which this socket is connected.

Public constructors
`SocketImpl()`

Public methods
`String`	`toString()` Returns the address and port of this socket as a `String`.

Protected methods
`abstract void`	`accept(SocketImpl s)` Accepts a connection.
`abstract int`	`available()` Returns the number of bytes that can be read from this socket without blocking.
`abstract void`	`bind(InetAddress host, int port)` Binds this socket to the specified local IP address and port number.
`abstract void`	`close()` Closes this socket.
`abstract void`	`connect(InetAddress address, int port)` Connects this socket to the specified port number on the specified host.
`abstract void`	`connect(SocketAddress address, int timeout)` Connects this socket to the specified port number on the specified host.
`abstract void`	`connect(String host, int port)` Connects this socket to the specified port on the named host.
`abstract void`	`create(boolean stream)` Creates either a stream or a datagram socket.
`FileDescriptor`	`getFileDescriptor()` Returns the value of this socket's `fd` field.
`InetAddress`	`getInetAddress()` Returns the value of this socket's `address` field.
`abstract InputStream`	`getInputStream()` Returns an input stream for this socket.
`int`	`getLocalPort()` Returns the value of this socket's `localport` field.
`<T> T`	`getOption(SocketOption<T> name)` Called to get a socket option.
`abstract OutputStream`	`getOutputStream()` Returns an output stream for this socket.
`int`	`getPort()` Returns the value of this socket's `port` field.
`abstract void`	`listen(int backlog)` Sets the maximum queue length for incoming connection indications (a request to connect) to the `count` argument.
`abstract void`	`sendUrgentData(int data)` Send one byte of urgent data on the socket.
`<T> void`	`setOption(SocketOption<T> name, T value)` Called to set a socket option.
`void`	`setPerformancePreferences(int connectionTime, int latency, int bandwidth)` Sets performance preferences for this socket.
`void`	`shutdownInput()` Places the input stream for this socket at "end of stream".
`void`	`shutdownOutput()` Disables the output stream for this socket.
`Set<SocketOption<?>>`	`supportedOptions()` Returns a set of SocketOptions supported by this impl and by this impl's socket (Socket or ServerSocket)
`boolean`	`supportsUrgentData()` Returns whether or not this SocketImpl supports sending urgent data.

Inherited methods

From class


        
          java.lang.Object

`Object`	`clone()` Creates and returns a copy of this object.
`boolean`	`equals(Object obj)` Indicates whether some other object is "equal to" this one.
`void`	`finalize()` Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
`final Class<?>`	`getClass()` Returns the runtime class of this `Object`.
`int`	`hashCode()` Returns a hash code value for the object.
`final void`	`notify()` Wakes up a single thread that is waiting on this object's monitor.
`final void`	`notifyAll()` Wakes up all threads that are waiting on this object's monitor.
`String`	`toString()` Returns a string representation of the object.
`final void`	`wait(long timeoutMillis, int nanos)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait(long timeoutMillis)` Causes the current thread to wait until it is awakened, typically by being notified or interrupted, or until a certain amount of real time has elapsed.
`final void`	`wait()` Causes the current thread to wait until it is awakened, typically by being notified or interrupted.

From interface


        
          java.net.SocketOptions

`abstract Object`	`getOption(int optID)` Fetch the value of an option.
`abstract void`	`setOption(int optID, Object value)` Enable/disable the option specified by optID.

Fields

address

Added in API level 1

protected InetAddress address

The IP address of the remote end of this socket.

fd

Added in API level 1

protected FileDescriptor fd

The file descriptor object for this socket.

localport

Added in API level 1

protected int localport

The local port number to which this socket is connected.

port

Added in API level 1

protected int port

The port number on the remote host to which this socket is connected.

Public constructors

SocketImpl

Added in API level 1

public SocketImpl ()

Public methods

toString

Added in API level 1

public String toString ()

Returns the address and port of this socket as a String.

Returns
`String`	a string representation of this socket.

Protected methods

accept

Added in API level 1

protected abstract void accept (SocketImpl s)

Accepts a connection.

Parameters
`s`	`SocketImpl`: the accepted connection.

Throws
`IOException`	if an I/O error occurs when accepting the connection.

available

Added in API level 1

protected abstract int available ()

Returns the number of bytes that can be read from this socket without blocking.

Returns
`int`	the number of bytes that can be read from this socket without blocking.

Throws
`IOException`	if an I/O error occurs when determining the number of bytes available.

bind

Added in API level 1

protected abstract void bind (InetAddress host, 
                int port)

Binds this socket to the specified local IP address and port number.

Parameters
`host`	`InetAddress`: an IP address that belongs to a local interface.
`port`	`int`: the port number.

Throws
`IOException`	if an I/O error occurs when binding this socket.

close

Added in API level 1

protected abstract void close ()

Closes this socket.

Throws
`IOException`	if an I/O error occurs when closing this socket.

connect

Added in API level 1

protected abstract void connect (InetAddress address, 
                int port)

Connects this socket to the specified port number on the specified host.

Parameters
`address`	`InetAddress`: the IP address of the remote host.
`port`	`int`: the port number.

Throws
`IOException`	if an I/O error occurs when attempting a connection.

connect

Added in API level 1

protected abstract void connect (SocketAddress address, 
                int timeout)

Connects this socket to the specified port number on the specified host. A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs.

Parameters
`address`	`SocketAddress`: the Socket address of the remote host.
`timeout`	`int`: the timeout value, in milliseconds, or zero for no timeout.

Throws
`IOException`	if an I/O error occurs when attempting a connection.

connect

Added in API level 1

protected abstract void connect (String host, 
                int port)

Connects this socket to the specified port on the named host.

Parameters
`host`	`String`: the name of the remote host.
`port`	`int`: the port number.

Throws
`IOException`	if an I/O error occurs when connecting to the remote host.

create

Added in API level 1

protected abstract void create (boolean stream)

Creates either a stream or a datagram socket.

Parameters
`stream`	`boolean`: if `true`, create a stream socket; otherwise, create a datagram socket.

Throws
`IOException`	if an I/O error occurs while creating the socket.

getFileDescriptor

Added in API level 1

protected FileDescriptor getFileDescriptor ()

Returns the value of this socket's fd field.

Returns
`FileDescriptor`	the value of this socket's `fd` field.

See also:

fd

getInetAddress

Added in API level 1

protected InetAddress getInetAddress ()

Returns the value of this socket's address field.

Returns
`InetAddress`	the value of this socket's `address` field.

See also:

address

getInputStream

Added in API level 1

protected abstract InputStream getInputStream ()

Returns an input stream for this socket.

Returns
`InputStream`	a stream for reading from this socket.

Throws
`IOException`	if an I/O error occurs when creating the input stream.

getLocalPort

Added in API level 1

protected int getLocalPort ()

Returns the value of this socket's localport field.

Returns
`int`	the value of this socket's `localport` field.

See also:

localport

getOption

Added in API level 33

protected T getOption (SocketOption<T> name)

Called to get a socket option.

Parameters
`name`	`SocketOption`: The socket option

Returns
`T`	the value of the named option

Throws
`UnsupportedOperationException`	if the SocketImpl does not support the option.
`IOException`	if an I/O error occurs, or if the socket is closed.

getOutputStream

Added in API level 1

protected abstract OutputStream getOutputStream ()

Returns an output stream for this socket.

Returns
`OutputStream`	an output stream for writing to this socket.

Throws
`IOException`	if an I/O error occurs when creating the output stream.

getPort

Added in API level 1

protected int getPort ()

Returns the value of this socket's port field.

Returns
`int`	the value of this socket's `port` field.

See also:

port

listen

Added in API level 1

protected abstract void listen (int backlog)

Sets the maximum queue length for incoming connection indications (a request to connect) to the count argument. If a connection indication arrives when the queue is full, the connection is refused.

Parameters
`backlog`	`int`: the maximum length of the queue.

Throws
`IOException`	if an I/O error occurs when creating the queue.

sendUrgentData

Added in API level 1

protected abstract void sendUrgentData (int data)

Send one byte of urgent data on the socket. The byte to be sent is the low eight bits of the parameter

Parameters
`data`	`int`: The byte of data to send

Throws
`IOException`	if there is an error sending the data.

setOption

Added in API level 33

protected void setOption (SocketOption<T> name, 
                T value)

Called to set a socket option.

Parameters
`name`	`SocketOption`: The socket option
`value`	`T`: The value of the socket option. A value of `null` may be valid for some options.

Throws
`UnsupportedOperationException`	if the SocketImpl does not support the option
`IOException`	if an I/O error occurs, or if the socket is closed.

setPerformancePreferences

Added in API level 1

protected void setPerformancePreferences (int connectionTime, 
                int latency, 
                int bandwidth)

Sets performance preferences for this socket.

Sockets use the TCP/IP protocol by default. Some implementations may offer alternative protocols which have different performance characteristics than TCP/IP. This method allows the application to express its own preferences as to how these tradeoffs should be made when the implementation chooses from the available protocols.

Performance preferences are described by three integers whose values indicate the relative importance of short connection time, low latency, and high bandwidth. The absolute values of the integers are irrelevant; in order to choose a protocol the values are simply compared, with larger values indicating stronger preferences. Negative values represent a lower priority than positive values. If the application prefers short connection time over both low latency and high bandwidth, for example, then it could invoke this method with the values (1, 0, 0). If the application prefers high bandwidth above low latency, and low latency above short connection time, then it could invoke this method with the values (0, 1, 2). By default, this method does nothing, unless it is overridden in a sub-class.

Parameters
`connectionTime`	`int`: An `int` expressing the relative importance of a short connection time
`latency`	`int`: An `int` expressing the relative importance of low latency
`bandwidth`	`int`: An `int` expressing the relative importance of high bandwidth

shutdownInput

Added in API level 1

protected void shutdownInput ()

Places the input stream for this socket at "end of stream". Any data sent to this socket is acknowledged and then silently discarded. If you read from a socket input stream after invoking this method on the socket, the stream's available method will return 0, and its read methods will return -1 (end of stream).

Throws
`IOException`	if an I/O error occurs when shutting down this socket.

See also:

shutdownOutput

Added in API level 1

protected void shutdownOutput ()

Disables the output stream for this socket. For a TCP socket, any previously written data will be sent followed by TCP's normal connection termination sequence. If you write to a socket output stream after invoking shutdownOutput() on the socket, the stream will throw an IOException.

Throws
`IOException`	if an I/O error occurs when shutting down this socket.

See also:

supportedOptions

Added in API level 33

protected Set<SocketOption<?>> supportedOptions ()

Returns a set of SocketOptions supported by this impl and by this impl's socket (Socket or ServerSocket)

Returns
`Set<SocketOption<?>>`	a Set of SocketOptions

supportsUrgentData

Added in API level 1

protected boolean supportsUrgentData ()

Returns whether or not this SocketImpl supports sending urgent data. By default, false is returned unless the method is overridden in a sub-class

Returns
`boolean`	true if urgent data supported

See also:

address